"SNA RESEARCH CONFERENCE - VOL. 36-1991" SECTION 10 LANDSCAPE Mr. Will Corley Section Chairman and Moderator 277 "SNA RESEARCH CONFERENCE - VOL. 36-1991" Establishment and Maintenance of Wildflowers on Erod- ible Sites W. L. Corley and James E. Dean Georgia Nature of Work: Stabilization of an erodible site is usually accomplished by seed- ing a nurse grass and/or companion legume (3). This nurse grass is seeded, fertil- ized, mulched, and managed or maintained to prevent erosion and sedimentation of down stream areas, and to improve wildlife habitat and visual resources. Since wildflowers are often desired to add low maintenance color for Improved visual and environmental enhancement effects (1,2) research was Initiated in 1988 to determine optimum seeding rates of appropriate nurse grasses and wildflowers and to determine fertilizer regimes for rapid establishment of a nurse grass while maintaining cost efficient wildflower color. Two infertile test sites were chosen: a loamy sand in extreme southwest Georgia and a heterogeneous clay subsoil in northcentral Georgia. Main plots were seeded spring and fall, according to requirements of the nurse grass. A typical southeast- ern wildflower mix was seeded at 10 Ibs./ac. (5 oz/K Ft2) into lightly tilled soil which had been oversprayed with Roundup to reduce competition from existing vegetation. Subplots consisted of the following grasses seeded simultaneously: tall fescue @ 35 Ibs./ac., Pensacola bahia @ 40 Ibs/ac., hulled common bermuda @ 7 Ibs./ac., and weeping lovegrass @ 3 Ibs./ac. Previous unpublished research had indicated that a 25 percent reduction in the nurse grass seeding rate was satisfac- tory to combine with usual wildflower seeding rates. Subplots were further divided into biannual fertilizer applications of granular 16-4-8 and Osmocote 18-6-12 at 500 and 1,000 Ibs./ac. All plantings were cultipacked and mulched lightly with clean wheat straw. Supplemental irrigation was not utilized. Data were collected over two years for nurse grass establishment, plant growth rates, and flowering or color effect of wildflowers. Results and Discussion: Detailed data are not presented but are available in publications cited. The following recommendations are submitted as guides to establish and maintaln wildflower color in grass plantings on erodible sites: 1 ) A seeding combination of 75 percent usual grass seeding rate + 10 lbs./ac. wildflower seed mix is recommended for all grasses except bahia. Wildflowers have failed to persist in all bahia seedings. 2) A typical southeastern wildflower mix will perform satisfactorily. Superior performance of a special mix for nurse grass compatibility is presented in Table 1. This mix can be custom blended by most wholesale wildflower seedsmen. 278 "SNA RESEARCH CONFERENCE - VOL. 36-1991" 3) Fertilizer rates of 500 to 1,000 Ibs./ac. will enhance seedling estab- lishment. Maintenance applications of 500 Ibs./ac. are usually suf- ficient. 4) Control of broadleaf weeds can be accomplished by mowing, spot spraying, or overspraying of appropriate herbicides. 5) Aggressive grasses can be checked by diluted sprays of grass specific herbicides, after soil erosion is not a problem. Significance to Industry: Low maintenance or conservascape color can be provided by wildflowers. When critical or erodible sites are seeded with grasses for erosion control, wildflowers can be economically added to the grassing specification. Management of wildflower meadows in these sites plays an important role in the durability and visual impact of a wildflower meadow for the Southeast. Literature Cited 1. Corley, W.L. and A. E. Smith, Jr. 1990. Evaluation of wildflower species and establishment procedures for Georgia roadsides. Ga. DOT Final Report ProJect 8604. DOT In House Publication. 2. Corley, W. L. 1990. Wildflower responses to fertilizer rates and formulations. SNA Res. Conf. Rept. 35:272-273. 3. Soil Conservation Service. 1987. Standards and Specifications for critical area planting. Tech. Guide No. GA-32. Table 1. Custom wildflower mix for nurse grass companion plantings on erod- ible sites. Taxa Common Name Bloom Season Color % Achillea millefolium White Yarrow Summer White 5 Centaurea cyanus Cornflower Spring Blue 10 Chamaecrista fasiculata Partridge Pea Fall Yellow 15 Chrysanthemum Oxeye Daisy Spring-Summer White 15 leucanthemum Coreopsis lanceolata Lance Coreopsis Summer Yellow 20 Gaillardia pulchella Annual Gaillardia Summer-Fall Yellow/Red 25 Rudbeckia hirta Blackeye Susan Summer-Fall Yellow 10 279 "SNA RESEARCH CONFERENCE - VOL. 36-1991" Seedbed Preparation Alternatives for Establishment of Wildflower Meadows and Beauty Spots W. L. Corley Georgia Nature of Work: Interest in wildflowers continue to grow in tandem with envi- ronmental and resource conservation concerns. Active and planned establishment of wildflowers on both public and private lands have served as query origins for proper establishment practices for wildflowers, whereby the goal of cost efficient landscape color can be successful for vegetation managers of public lands, landscape contractors, and backyard gardeners. A test was initiated to determine optimal soil preparatlon for wildflower seedling establishment while minimizing competi- tion from weed seedlings. A test site was selected in clay loam subsoil with little inherent fertility and pH of 5.8. During late summer and fall the following seedbed preparation treatments were implemented on a site containing common bermuda grass and miscellaneous weeds: (1) mow + Roundup overspray, (2) mow + Roundup + shallow till, (3) mow + Roundup and Treflan tank mix + shallow till, (4) multiple deep tillage, (5) solarization, and (6) fumigation with Basamid. Light tillage disturbed the soil only 1 to 2 inches deep, while conventional tillage penetrated 6 to 8 inches. Multiple deep tillages were necessary to suppress weed seedlings stimulated by the previous tillage. Fumigation consisted of deep tillage, incorporation of fumigant granules, and sealing under plastic for several weeks prior to planting. Solarization was ac- complished by all the procedures for fumigation except no fumigant was applied. A landscape color southeastern wildflower mix was seeded at 15 pounds per acre during early winter. Wheat straw mulch was applied at approximately one-half inch depth over all treatments. Ratings for wildflower establishment, flowering effect, and weed competition were recorded monthly during the growing season. The monocot specific herbicide, Poast, was oversprayed during April and June to reduce competition from grassy weeds. Results and Discussion: Table 1 shows that the practice of drill seeding wild- flowers into dormant turf during winter months can produce good results. However, timing for adequate soil moisture is critical since a straw mulch is not used. Dormant turf can serve as a partial mulch for seedling establishment. When shallow tilling is utilized, weed seedling population can seriously compete with wildflower stands. A short term preemergent herbicide such as Treflan can significantly reduce weed seedling competition. Herbicide application should be made 4 to 6 weeks prior to planting. Incorporation by rainfall or irrigation is necessary. Multiple tillage produced a good seedbed. Both solarization and fumigation treatments resulted in excellent wildflower establishment and weed suppression. These two seedbed preparation techniques require warm soils for effectiveness, thus implementation by late summer is necessary. 280 "SNA RESEARCH CONFERENCE - VOL. 36-1991" Significance to Industry: Cost efficient landscape color can be provided by wildflower meadows and beauty spots. Several methods for seedbed preparation are optimal for landscape managers, according to landscape maintenance budgets and desired effects of the wildflower plantings. Where low costs (pennies per square foot) are desired or critical, multiple tillings or the use of short term preemergent herbicides are viable options in seedbed preparation. Both solarization and fumiga- tion produce good results where resources are available. Table 1. Effects of tillage methods on wildflower species establishment and weed suppression, 1989-1990. Wildflower Weed Tillage method Establishment1 Suppression2 Mow + Roundup Good Good Mow + Roundup + Shallow Till Fair Poor Mow + Roundup + Treflan + Shallow Till Excellent Good DeepTill Twice Excellent Good Solarization Excellent Good Fumigation Excellent Good 1 Rated subjectively at seeding rate of 15 Ibs/ac. 2 Rated subjectively on winter, spring and summer weed emergence. Literature Cited 1. Corley, W.L. and A. E. Smieh, Jr. 1989. Evaluation of wildflower plant species and establishment procedures for Georgia road sites. GDOT Research Project No. 8604 Final Report. 2. Corley, W. L. 1990. Wildflower responses to fertilizer rates and formulations. SNA Research Conf. Proc. 35:272-273. 3. Erusha, K.S., C. Fricker, R. C. Shearman, and D. H. Steinegger. 1991. Effect of preemergent herbicide on wildflower establishment. HortScience 26(2): 209. 4. North Carolina DOT. 1989. Wildflowers on North Carolina roadsides. NC DOT Landscape Unit Publ. 281 "SNA RESEARCH CONFERENCE - VOL. 36-1991" Cold Hardiness Potential of Four Selections of Raphiolepis umbellata Orville M. Lindstrom and Will L. Corley Georgia Nature of Work: Yeddo raphiolepis or Indian Hawthorn (Raphiolepis umbellata Makino.) is a popular plant throughout USDA hardiness zones 8 through 10 (Dirr, 1990). To increase its geographic range of adaptability it is necessary to increase its cold